Effect of A-769662, a direct AMPK activator, on expression and activity in mice heart tissue.

Objectives: TLR-4 activates a number of inflammatory signaling pathways. Also, AMPK could be involved in anti-inflammatory signaling. The aim of this study was to identify whether stimulation of AMPK could inhibit LPS-induced -4 gene expression in mice hearts.

Materials And Methods: Heart AMPK activity and/or -4 expression was stimulated in different mice groups, using respectively IP injection of A-769662 (10 mg/kg) and LPS (2 mg/kg) or a combination of both agents. Moreover, compound-C (20 mg/kg), as an AMPK antagonist, was intraperitoneally co-administrated with both A-769662 and LPS in another group to investigate the role of AMPK activity on -4 regulation. After 8 hr, in addition to peripheral neutrophil cell count, myocardial p-AMPK, p-ACC as well as MyD88 protein contents and -4 expression was assessed by Western blotting and real-time qRT-PCR, respectively. TNF-α and IL-6 expression levels were also determined by ELISA.

Results: LPS induced heart -4 expression (<0.001) associating with an increase in the myocardial MyD88 protein content (<0.001), elevation of heart TNF-α (<0.01) and IL-6 (<0.05) concentrations, and rise in the peripheral neutrophil cell count (<0.001). Administration of A-769662 decreased LPS-induced -4 expression (<0.01) and alleviated peripheral neutrophil cell count (<0.01). The inhibitory effect of A-769662 on LPS-induced -4 expression was reversed by antagonizing AMPK with compound-C (<0.001) which reduced p-AMPK (<0.05) and p-ACC (<0.01) myocardial protein contents in the LPS+A-769662 group.

Conclusion: This study demonstrated that activation of AMPK, by A-769662 agent, could inhibit -4 expression and activity, suggesting a link between AMPK and Tlr-4 in heart tissue.